C2.2 Neural signaling Flashcards
Propagation of nerve impulse
Action potential in one part of the axon triggers an action potential in the next part
- Depolarization (opening of voltage gated Na+ channels) - process
Na+ channels open if resting potential rises to the threshold potential of -50mV - triggers the opening of more Na+ channels (positive feedback loop) until influx of NA+ reaches +30mV
- Repolarization (opening of voltage gated K+ channels) - process
Na+ channels close, triggers opening of K+ channels; causing K+ to diffuse out of neuron until -70mV reached
Summation
The accumulative effect of multiple releases of neurotransmitters to trigger an action potential
Resting potential of a Neuron
-70mv
Charge imbalance of Neuron
Inside of the Neuron relatively negative compared to the outside
Saltatory conduction
The jumping/skipping motion of nerve impulses from one node of Ranvier to another - speeds up nerve propagation
Nerve conduction velocity
- Velocity increased by Myelination
- Velocity increased by larger surface area
- Velocity increased at warmer temperature
Action potential
Rapid change in electrical charge across the neuron (inside and outside)
Exogenous chemicals
Chemicals which come from outside of the body, and enter the body
Neonicotinoid pesticides
Causes permanent binding of acetylcholine to Na+ ion channel receptors, causing irreversible flow of Na+ into muscles causing paralysis and death.
Acetylcholine (muscles) - process
Binds to post-synaptic Na+ ion channel receptors, opening them. Acetylcholine is then rapidly broken down by enzyme acetylcholinesterase, closing the channel.
Cocaine
Binds to dopamine receptors, blocking reuptake of dopamine, causing build up of dopamine in synaptic cleft & continuous excitement of post-synaptic neuron.
Excitatory Neurotransmitters
Make membrane potentials less negative (depolarize)
Inhibitory Neurotransmitters
Make membrane potentials more negative (repolarize)
“All or nothing” Principle
Unless the threshold potential is reached there is no action potential
Resting potential
Imbalance across neuron membrane, due to unequal number of ions - when 3 Na+ ions are pumped out, only 2 K+ ions are pumped in.
Dentrites
branched extensions that receive electrical signals and conduct them toward the soma
Soma
contains the nucleus, processes transmissions
Axon
thin extension of a neuron that transmits electrical impulses away from the cell body toward other neurons, muscles, or glands
